METHOD AND SYSTEM FOR PRE-IGNITION CONTROL

• US 20140000555A1
• Filed: 06/29/2012
• Published: 01/02/2014
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Glugla, Chris Paul, Czekala, Michael Damian
• Granted Patent: US 8,997,723 B2
• Time in Patent Office: Days
• US Class Current: 123/305
• CPC Class Codes: F02D 37/02 one of the functions being ignition
• CPC Class Codes: F02D 41/008 Controlling each cylinder individually
• CPC Class Codes: F02D 41/04 Introducing corrections for particular operating conditions F02D41/14 takes precedence
• CPC Class Codes: F02M 26/04 with a single turbocharger
• CPC Class Codes: F02M 26/43 in which exhaust from only one cylinder or only a group of cylinders is directed to the intake of the engine
• CPC Class Codes: F02P 3/0453 Opening or closing the primary coil circuit with semiconductor devices
• CPC Class Codes: F02P 5/15 Digital data processing
• CPC Class Codes: F02P 5/1504 with particular means during a transient phase, e.g. acceleration, deceleration, gear change during starting F02P5/1506
• CPC Class Codes: F02P 9/002 Control of spark intensity, intensifying, lengthening, suppression by means of current control in the storage devices F02P3/05, F02P3/09, during starting F02P15/12
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and systems are provided for reducing late burn induced cylinder pre-ignition events. In response to a late burn combustion event in a cylinder, ignition coil dwell time is extended in the cylinder to reduce unintended combustion delays. In addition, pre-ignition mitigating actions are performed in a neighboring cylinder that may be prone to pre-ignition induced by the late combustion event.

Claims

1. A method for an engine, comprising

in response to timing of combustion in a cylinder being later than a threshold, selectively increasing spark ignition output for the combustion.

2. The method of claim 1, wherein increasing ignition output includes extending a dwell time of a spark ignition coil.

3. The method of claim 2, wherein the extending of the dwell time is based on a torque ratio of desired combustion timing to actual combustion timing.

4. The method of claim 1, wherein the combustion in the cylinder is a first combustion event, and wherein temporarily increasing spark ignition output includes increasing spark ignition output for the first combustion event in the cylinder and resuming spark ignition output for a second, subsequent combustion event.

5. The method of claim 1, wherein the cylinder is a first cylinder, and wherein the selective increasing is performed to reduce a likelihood of pre-ignition in a second cylinder, the second cylinder receiving exhaust residuals from the first cylinder.

6. The method of claim 5, wherein the threshold is based on one or more of a pre-ignition history of the first cylinder, a pre-ignition history of the second cylinder, an amount of EGR in the first cylinder, and an amount of exhaust residuals in the first cylinder.

7. The method of claim 5, further comprising, selectively enriching the second cylinder based on the timing of combustion in the first cylinder, a degree of richness increased as a difference of the combustion timing in the first cylinder from the threshold increases.

8. A method for a boosted engine, comprising,

during an over-torque condition,

reducing engine torque by retarding spark timing;

and

adjusting spark ignition energy for a cylinder combustion event based on a torque reduction ratio at the retarded spark timing.

9. The method of claim 8, wherein the adjusting includes, as the torque reduction ratio falls below a threshold, selectively increasing the spark ignition energy for the cylinder combustion event.

10. The method of claim 9, wherein the spark ignition energy is selectively increased for the given cylinder combustion event, and wherein the spark ignition energy is reduced for a subsequent cylinder combustion event.

11. The method of claim 9, wherein selectively increasing the spark ignition energy includes increasing an ignition coil dwell time as a difference between the torque reduction ratio and the threshold increases

12. The method of claim 11, wherein increasing the ignition coil dwell time includes initiating charging of the ignition coil at an earlier time and charging the ignition coil to a higher peak coil current.

13. The method of claim 9, wherein the threshold is based on an amount and temperature of exhaust residuals in the cylinder.

14. The method of claim 13, wherein the cylinder is a first cylinder, and wherein the threshold is further based on a pre-ignition history of a second cylinder receiving exhaust residuals from combustion in the first cylinder.

15. An engine system, comprising:

an engine including a plurality of cylinders;

a turbocharger for providing engine boost;

an ignition coil supplying electrical energy to a spark plug; and

a control system with computer-readable instructions for,

retarding spark ignition timing in a cylinder to reduce combustion torque; and

increasing an ignition coil dwell time during a combustion event in the cylinder based on a torque ratio achieved at the retarded spark ignition timing.

16. The system of claim 15, wherein the increasing includes, increasing ignition coil dwell time to a longer dwell time with a factor that is based on a distance of the torque ratio at the retarded spark ignition timing from a threshold.

17. The system of claim 16, wherein increasing an ignition coil dwell time includes initiating charging of the ignition coil at an earlier time so as to discharge the ignition coil at the retarded spark timing and charging the ignition coil to a higher peak coil current.

18. The system of claim 17, wherein the combustion event in the cylinder is a first combustion event in a first cylinder, and wherein the threshold is based on one or more of a cylinder load of the first cylinder, an amount of exhaust residuals generated in the first cylinder, an engine boost level, a temperature of exhaust residuals generated in the first cylinder, an amount of EGR in the first cylinder, and a pre-ignition history of a second cylinder receiving exhaust residuals from the first cylinder.

19. The system of claim 18, wherein the control system includes further instructions for enriching the second cylinder in response to the torque ratio in the first cylinder.

20. The system of claim 19, wherein a degree of richness of the enrichment is increased as the distance between the torque ratio at the retarded spark ignition timing and the threshold increases.